Gerotor motors have pressure imbalances. These imbalances typically are caused by the selective pressurization of the gerotor cells utilized therein as well as the pressurization of the device necessitated by the interconnection thereof to operating ports, typically pressure and return. This is true whether the device has a rotor valve, separate rotating valve, separate orbiting valve, or otherwise. Over the years gerotor motors have modified in view of this pressure imbalance. Examples of motors together with a pressure compensating mechanism include White U.S. Pat. No. 4,717,320 entitled Gerotor Motor Balancing Plate; White U.S. Pat. No. 4,940,401 entitled Lubrication Fluid Circulation Using A Distance Valve Pump With A Bidirectional Flow; White U.S. Pat. No. 6,074,188 entitled Multiplate Hydraulic Motor Valve; and, Bernstrom U.S. Pat. No. 4,976,594 entitled Gerotor Motor And Improved Pressure Balancing Therefor. (See also White U.S. Pat. No. 6,257,853 entitled Hydraulic Motor With Pressure Compensating Manifold.) Each one of these devices in some way compensate for the different pressurization therein: In quick generality, U.S. Pat. No. 4,717,320 by bowing a balancing plate back against the rotor; U.S. Pat. No. 4,940,401 by including a piston valve to move fluid bidirectionally in and out of the internal cavity; and, U.S. Pat. No. 6,074,188 by including check balls to provide for the unimpeded laminar flow to the passage having least pressure. The U.S. Pat. No. 6,257,853 patent is a rear-ported device which includes a pressure compensating plate between the manifold and port plate; and, Bernstrom U.S. Pat. No. 4,976,594 includes a stationary valve member which biases the star member in respect to the stationary valve member.
Each of these motors is in its own way quite complex in both design, manufacture, and operation. In addition, due to delays in pressurizations, there is a corresponding delay in the operation of most of these devices. This is specially critical in low-speed low-volume high-torque operations and on direction change.